1. Field of the Invention
The present invention relates to a magnetic disk apparatus and in particular, to the magnetic disk apparatus reduced in costs with miniaturized and diversified printed-circuit boards.
2. Description of the Prior Art
A conventional magnetic disk apparatus generally has a single printed-circuit board for a single disk enclosure. The single printed-circuit board mounts all the circuits for controlling the disk enclosure.
In case of exchanging a conventional magnetic disk apparatus to another conventional magnetic disk apparatus for the purpose of increasing the capacity of the magnetic disk apparatus constituting a system or preserving the former magnetic disk apparatus as a spare magnetic disk apparatus, the printed-circuit board as well as the disk enclosure are exchanged for another set, because the printed circuit board and the disk enclosure are incorporated in one.
Referring to FIG. 5, disk enclosure 82 comprises a storage medium (not shown), a spindle motor (not shown) for rotating the storage medium, a voice coil motor (not shown) for driving a magnetic head (not shown) and rotating an actuator (not shown), a carriage (not shown) for carrying the magnetic head, a base (not shown) for mounting the storage medium, and a recording/reproduced signal compensation circuit (not shown) for processing a record/reproduced signal to/from the magnetic head. The magnetic head is mounted on the carriage.
Recording/reproduction of a signal to/from the storage medium is performed by the recording/reproduced signal compensation circuit and the magnetic head under the control of recording/reproducing control circuit 83 mounted on printed-circuit board 81. SPM/VCM (Spindle Motor/Voice Coil Motor) control circuit 88 controls the rotation of the storage medium through the spindle motor and the position of the magnetic head through the voice coil motor. Interface control circuit 87 controls communication protocols with upper system 90 which are exchanged through connectors 89 and 91 and a bus cable therebetween. Parameter-holding circuit 86 holds parameters of the storage medium which correspond to a type of recording system and is such as a ROM. Analog/digital converter 84 converts an analog signal reproduced from the storage medium into a digital signal. Processor 85 controls recording/reproducing control circuit 83, parameter-holding circuit 86, interface control circuit 87, and SPM/VCM control 88.
As explained above, the conventional magnetic disk apparatus has a single printed-circuit board for a single disk enclosure. Therefore, in case of exchanging a conventional magnetic disk apparatus to another conventional magnetic disk apparatus, it is inevitable to exchange a printed-circuit board which is originally needless to be exchanged in addition to a disk enclosure, which results in an increase in cost of the exchange.
In case of a removable medium, after purchasing one removable medium and a recording/reproduction device, it is needed to purchase only another removable medium to increase the capacity. Therefore, the removable medium has a merit in capacity/cost ratio. On the other hand, in case of a magnetic disk apparatus, it is needed to purchase not only a disk enclosure but also a printed-circuit board which is unrelated to the increase of the capacity to increase the capacity.
In addition, the structure of a conventional disk apparatus in which a single printed-circuit board mounting all the circuits is combined with a single disk enclosure is a factor which prevents miniaturization of the apparatus and a breakaway of the apparatus from form factors.